1. Field of the Invention
The present invention relates to an information storing disk for storing a system stream, and an apparatus and a method for reproducing the system stream from the information storing disk. In particular, the present invention relates to an information storing disk for allowing a plurality of reproduction apparatuses having different levels of performance, such as data processing speed, to have the same wait time before the reproduction of the system stream starts, and an apparatus and a method for reproducing the system stream from the information storing disk.
2. Description of the Related Art
Conventionally known optical disks for storing audio information and moving picture information to be reproduced therefrom include compact disks (CDs) and laser disks (LDs).
A CD is an optical disk having a diameter of 12 cm and stores digital data obtained by encoding music information using an encoding technology referred to as linear PCM. CDs have been utilized as a medium for storing digital data for music applications.
An LD is an optical disk having a diameter of 30 cm and stores moving picture information, along with audio information, in the form of analog signals. LDs have been utilized as a medium for storing analog data for video applications such as movies.
Recently, new types of optical disks have been introduced. One of such new types of optical disks is an optical disk having a diameter of about 12 cm which realizes long-time recording/storing and a sufficiently high quality by efficient compression of music information and/or moving picture information including audio information. Another type of optical disk has a file structure with which data transmission with computers and communication devices is performed relatively easily.
Under such circumstances, an information storing medium which realizes storing and reproduction of audio data with a higher quality than compact disks have been demanded. As such an information storing medium, an optical disk in conformity with the DVD-Video format have been developed and implemented. Such an optical disk realizes storing and reproduction of audio data of a high quality of linear PCM, 96 kHzxc2x724-bit sampling. However, with the DVD-Video format, it is impossible to reproduce high quality linear PCM multi-surround audio information or higher quality audio information.
High quality audio data contains a large amount of data and thus requires a high data transfer speed of audio data.
The present inventors have found, through many years of research and development on optical disks for storing high quality audio data, that the wait time before the start of reproduction of high quality audio data causes various problems.
Before the start of reproduction of information stored on an optical disk, the wait time is required, which is the time period from when one system stream to be reproduced among one or more system streams stored on the optical disk is determined until the reproduction of the one system stream is started. The wait time is also referred to as the xe2x80x9cstart-up periodxe2x80x9d. A plurality of reproduction apparatuses having different levels of performance, such as data processing speed, usually have different start-up periods.
In the case of, for example, high quality audio data having a stream structure of the MPEG format, the start-up period includes time period Ts, time period Tc, and time period Tm. Time period Ts is a period required for the reproduction apparatus to seek to the position, on the optical disk, storing the audio data. Time period Tc is a period from when the audio data is input to a decoder until the first correct decoded audio data is output from the decoder. Time period Tc includes a period for adjusting output timing of a system stream with reference to a PTS (Presentation Time Stamp) included in the system stream and a period for examining whether or not the audio data included in the system stream is correct. Time period Tm is a period for transition of a muting circuit in an analog output section from a mute state to a non-mute state.
In the case where a system decoder and an audio decoder are accommodated in separate chassis or mounted on separate LSIs, the start-up period is further extended because adjustment of the output timing based on the PTS and the examination on whether or not the audio data is correct need to be performed separately.
When the start-up period is extended, malfunction that the output timing for the system stream is not properly adjusted may undesirably occur in a specific reproduction apparatus and thus the leading audio data in the system stream is not reproduced.
When a plurality of reproduction apparatuses have different start-up periods, the inter-tune interval of an optical disk varies in accordance with the reproduction apparatus used. In such case, disk creators cannot uniformly set the inter-tune interval, which is significantly disadvantageous to the disk creators and users.
According to one aspect of the invention, an information storing disk includes at least one system stream stored thereon. The at least one system stream includes a silent cell for defining a silent period and an audio cell for defining audio data to be reproduced after the silent period. The silent period is a period to be silent, which is from when one system stream to be reproduced among at least one system stream is determined until reproduction of an audio cell included in the one system stream is started.
In one embodiment of the invention, the silent period includes a period required by a reproduction apparatus after one system stream to be reproduced among at least one system stream is determined until reproduction of the one system stream is started.
In one embodiment of the invention, the information storing disk further includes information indicating the order of reproducing a plurality of system streams. The silent period is a period to be silent, which is from when reproduction of one of the plurality of system streams is terminated until reproduction of an audio cell included in the next system stream is started.
In one embodiment of the invention, the silent cell and the audio cell each include audio data encoded in an identical encode mode, and an output level of the audio data included in the silent cell is substantially zero.
In one embodiment of the invention, the system stream includes a time stamp for defining output timing at a prescribed interval, a presentation period of the audio cell is determined based on a difference between a first time stamp and a final time stamp included in the audio cell, and the silent period is determined based on a difference between a first time stamp and a final time stamp included in the silent cell.
According to another aspect of the invention, a reproduction apparatus for reproducing information stored on an information storing disk is provided. The information storing disk including at least one system stream stored thereon. The at least one system stream includes a silent cell for defining a silent period and an audio cell for defining audio data to be reproduced after the silent period. The silent period is a period to be silent, which is from when one system stream to be reproduced among at least one system stream is determined until reproduction of an audio cell included in the one system stream is started. The reproduction apparatus includes a reading section for reading a system stream to be reproduced among the at least one system stream stored on the information storing disk, and a reproduction section for reproducing a part of the silent cell and reproducing the audio cell, from a point in the silent cell included in the read system stream.
In one embodiment of the invention, the silent period includes a period required by a reproduction apparatus after one system stream to be reproduced among at least one system stream is determined until reproduction of the one system stream is started.
In one embodiment of the invention, the information storing disk further includes information indicating the order of reproducing a plurality of system streams. The silent period is a period to be silent, which is from when reproduction of one of the plurality of system streams is terminated until reproduction of an audio cell included in the next system stream is started.
In one embodiment of the invention, the silent cell and the audio cell each include audio data encoded in an identical encode mode, and an output level of the audio data included in the silent cell is substantially zero.
In one embodiment of the invention, the system stream includes a time stamp for defining output timing at a prescribed interval, a presentation period of the audio cell is determined based on a difference between a first time stamp and a final time stamp included in the audio cell, and the silent period is determined based on a difference between a first time stamp and a final time stamp included in the silent cell.
According to still another aspect of the invention, a reproduction method for reproducing information stored on an information storing disk is provided. The information storing disk includes at least one system stream stored thereon. The at least one system stream includes a silent cell for defining a silent period and an audio cell for defining audio data to be reproduced after the silent period. The silent period is a period to be silent, which is from when one system stream to be reproduced among at least one system stream is determined until reproduction of an audio cell included in the one system stream is started. The reproduction method includes the steps of reading a system stream to be reproduced among the at least one system stream stored on the information storing disk, and reproducing a part of the silent cell and reproducing the audio cell, from a point in the silent cell included in the read system stream.
In one embodiment of the invention, the silent period includes a period required by a reproduction apparatus after one system stream to be reproduced among at least one system stream is determined until reproduction of the one system stream is started.
In one embodiment of the invention, the information storing disk further includes information indicating the order of reproducing a plurality of system streams. The silent period is a period to be silent, which is from when reproduction of one of the plurality of system streams is terminated until reproduction of an audio cell included in the next system stream is started.
In one embodiment of the invention, the silent cell and the audio cell each include audio data encoded in an identical encode mode, and an output level of the audio data included in the silent cell is substantially zero.
In one embodiment of the invention, the system stream includes a time stamp for defining output timing at a prescribed interval, a presentation period of the audio cell is determined based on a difference between a first time stamp and a final time stamp included in the audio cell, and the silent period is determined based on a difference between a first time stamp and a final time stamp included in the silent cell.
Thus, the invention described herein makes possible the advantages of providing an information storing disk for allowing a plurality of reproduction apparatuses having different levels of performance, such as data processing speed, to have an equal wait time (start-up period) before the reproduction of a system steam starts, and an apparatus and a method for reproducing the system stream from the information storing disk.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.